Rainfall Erosivity in Europe

What is rainfall erosivity (R-Factor)?

Rainfall erosivity is the kinetic energy of raindrop's impact and the rate of associated runoff. The R-factor is a multi-annual average index that measures rainfall's kinetic energy and intensity to describe the effect of rainfall on sheet and rill erosion. Among the factors used within RUSLE and its earlier version, the Universal Soil Loss Equation (USLE), rainfall erosivity is of high importance as precipitation is the driving force of erosion and has a direct impact on the detachment of soil particles, the breakdown of aggregates and the transport of eroded particles via runoff. A precise assessment of rainfall erosivity requires recordings of precipitation at short time intervals (1 – 60 minutes) for a period of at least several years. The rainfall erosivity is calculated by multiplying the kinetic energy by the maximum rainfall intensity during a period of 30-minutes for each rainstorm. The R-factor accumulates the rainfall erosivity of individual rainstorm events and averages this value over multiple years.

REDES: Rainfall Erosivity Database on the European Scale

The Rainfall Erosivity Database on the European Scale (REDES) includes high temporal resolution precipitation data and the claculated R-factor from 1,675 precipitation stations within the European Union (EU) and Switzerland. The Rainfall Erosivity Database on European Scale (REDES) of precipitation stations is the result of calculating the R-factor for a total of 26,394 years with a mean value of 17.1 years per station. The data collection exercise of high temporal resolution data began in March 2013 and was concluded in May 2014. Data for additional 134 stations were collected in 2015. For the present rainfall erosivity data collection exercise, a participatory approach has been followed in order to collect data from all Member States (Aknowledgments). The precipitation data collected from the 28 countries across Europe have different temporal resolutions: 60-min, 30-min, 15-min, 10-min and 5-min. In order to homogenise the R-factor results calculated using different time-step data, conversion factors were established to have the data at the 30-min temporal resolution (reference).

R-factor in Europe

The purpose of this study is to assess rainfall erosivity in Europe in the form of the RUSLE R-factor, based on the best available datasets in Europe. We used the Rainfall Erosivity Database on the European Scale(REDES) which contains 1,675 precipitation stations in all European Union(EU) Member States and Switzerland, with temporal resolutions of 5 to 60 minutes. The R-factor values calculated from precipitation data of different temporal resolutions were normalised to R-factor values with temporal resolutions of 30 minutes using linear regression functions. Precipitation time series ranged from a minimum of 5 years to maximum of 40 years. The average time series per precipitation station is around 17.1 years, the most datasets including the first decade of the 21st century. Gaussian Process Regression(GPR) has been used to interpolate the R-factor station values to a European rainfall erosivity map at 1 km resolution. The covariates used for the R-factor interpolation were climatic data (total precipitation, seasonal precipitation, precipitation of driest/wettest months, average temperature), elevation and latitude/longitude. The mean R-factor for the EU plus Switzerland is 722 MJ mm ha-1 h-1 yr-1, with the highest values (>1,000 MJ mm ha-1 h-1 yr-1) in the Mediterranean and alpine regions and the lowest (Less than 500 MJ mm ha-1 h-1 yr-1) in the Nordic countries. The erosivity density (erosivity normalised to annual precipitation amounts) was also highest in Mediterranean regions which implies high risk for erosive events and floods.

Rainfall erosivity (R-factor) in Europe is a key parameter for estimating soil erosion loss and soil erosion risk, but the use of this dataset can be widely extended to other applications: landslide risk assessment, flood risk forecasting, Hydrology, post-fire conservation measures, agricultural management and design of crop rotation scenarios.

Further studies in this topic have been developed. You can find more information on:

Data and Maps

The Rainfall Erosivity and the other climatic data is in Raster format. The public user can download the following datasets a) Rainfall erosivity in Europe (R-factor) b) Erosivity Density c) The standard error of the estimates d) Monthly rainfall erosivity in Europe; e) Seasonal erosivity in Europe; f) Indicators of rainfall erosivity; g) Future rainfall erosivity (projections for 2050 based on climate change) h) Monthly R-factor in Greece, Annual R-factor (plus standard error) in Greece, seasonal Erosivity Density in Greece i) The R-factor in Switzerland (as calculated in 2012) and the code for calculating R-factor j) The Rainfall Erosivity Database at European Scale (REDES) 1,675 stations with R-factor data.

To get access to the data and the code, please compile the online form; instructions will then follow how to download the datasets.

Fig. 1: R-factor high resolution(2015)

Fig. 2: Erosivity Density

Fig. 3: Mean annual precipitation & R-factor Stations

Note: Due to increased number of requests, we have estimate the Erosivity factor in the whole European Continent. The new dataset (including Iceland, Norway, Serbia, FYROM, Albania, Montenegro, Belarus and Ukraine) is available upon request to ESDAC.